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Find video protocols related to scientific articles indexed in Pubmed.
Phosphorylation of Coat Protein by Protein Kinase CK2 Regulates Cell-to-Cell Movement of Bamboo mosaic virus Through Modulating RNA Binding.
Mol. Plant Microbe Interact.
PUBLISHED: 07-16-2014
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In this study, we investigated the fine regulation of cell-to-cell movement of Bamboo mosaic virus (BaMV). We report that the coat protein (CP) of BaMV is phosphorylated in planta at position serine 241 (S241), in a process involving Nicotiana benthamiana casein kinase 2? (NbCK2?). BaMV CP and NbCK2? colocalize at the plasmodesmata, suggesting that phosphorylation of BaMV may be involved in its movement. S241 was mutated to examine the effects of temporal and spatial dysregulation of phosphorylation on i) the interactions between CP and viral RNA and ii) the regulation of cell-to-cell movement. Replacement of S241 with alanine did not affect RNA binding affinity but moderately impaired cell-to-cell movement. A negative charge at position 241 reduced the ability of CP to bind RNA and severely interfered with cell-to-cell movement. Deletion of residues 240 to 242 increased the affinity of CP to viral RNA and dramatically impaired cell-to-cell movement. A threonine at position 241 changed the binding preference of CP toward genomic RNA and inhibited cell-to-cell movement. Together, these results reveal a fine regulatory mechanism for the cell-to-cell movement of BaMV, which involves the modulation of RNA binding affinity through appropriate phosphorylation of CP by NbCK2?.
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Identification of posttraumatic growth trajectories in the first year after breast cancer surgery.
Psychooncology
PUBLISHED: 04-17-2014
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Empirical studies of the relationship between posttraumatic growth (PTG) and adjustment outcomes reveal a fairly inconclusive picture. We argue that the inconsistent findings are likely due to the heterogeneity of the PTG experience over time. In this regard, we predicted that individuals with different PTG trajectories vary in the level of adjustment and the correlational patterns between PTG and adjustment.
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Using cognitive modelling to investigate the psychological processes of the Go/NoGo discrimination task in male abstinent heroin misusers.
Addiction
PUBLISHED: 04-11-2014
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To use cognitive modelling to investigate psychological processes underlying decision-making in male abstinent heroin misusers (AHMs).
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One-year follow up of PTSD and depression in elderly aboriginal people in Taiwan after Typhoon Morakot.
Psychiatry Clin. Neurosci.
PUBLISHED: 02-21-2014
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This paper describes a 1-year follow-up of post-traumatic stress disorder (PTSD) symptomatology and depression in an elderly minority population who experienced Typhoon Morakot in Taiwan.
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Two key arginine residues in the coat protein of Bamboo mosaic virus differentially affect the accumulation of viral genomic and subgenomic RNAs.
Mol. Plant Pathol.
PUBLISHED: 01-08-2014
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The interactions between viral RNAs and coat proteins (CPs) are critical for the efficient completion of infection cycles of RNA viruses. However, the specificity of the interactions between CPs and genomic or subgenomic RNAs remains poorly understood. In this study, Bamboo mosaic virus (BaMV) was used to analyse such interactions. Using reversible formaldehyde cross-linking and mass spectrometry, two regions in CP, each containing a basic amino acid (R99 and R227, respectively), were identified to bind directly to the 5' untranslated region of BaMV genomic RNA. Analyses of the alanine mutations of R99 and R227 revealed that the secondary structures of CP were not affected significantly, whereas the accumulation of BaMV genomic, but not subgenomic, RNA was severely decreased at 24 h post-inoculation in the inoculated protoplasts. In the absence of CP, the accumulation levels of genomic and subgenomic RNAs were decreased to 1.1%-1.5% and 33%-40% of that of the wild-type (wt), respectively, in inoculated leaves at 5 days post-inoculation (dpi). In contrast, in the presence of mutant CPs, the genomic RNAs remained about 1% of that of wt, whereas the subgenomic RNAs accumulated to at least 87%, suggesting that CP might increase the accumulation of subgenomic RNAs. The mutations also restricted viral movement and virion formation in Nicotiana benthamiana leaves at 5 dpi. These results demonstrate that R99 and R227 of CP play crucial roles in the accumulation, movement and virion formation of BaMV RNAs, and indicate that genomic and subgenomic RNAs interact differently with BaMV CP.
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Genetic diversity and evolution of satellite RNAs associated with the bamboo mosaic virus.
PLoS ONE
PUBLISHED: 01-01-2014
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Satellite RNAs (satRNAs) are subviral agents that depend on cognate helper viruses for genome replication and encapsidation. Their negative impacts on helper viruses have been exploited to control plant viral diseases. SatBaMV is a commonly found satRNA associated with Bamboo mosaic virus (BaMV) that infects diverse bamboo species in the field. To investigate the genetic diversity and evolution of satRNAs, we examined seven satBaMV populations derived from five bamboo species and cultivars from Taiwan, China, and India and one from the greenhouse. We found 3 distinct clades among the seven populations. Clade I is consisted of all satBaMV isolates, except for those from Dendrocalamus latiflorus in Taiwan and Bambusa vulgaris in India, which belong to Clades II and III, respectively. Interestingly, nucleotide diversity was lower for Clade I than II and III. However, the nucleotide diversity did not seem to depend on bamboo species or geographic location. Our population genetic analyses revealed the presence of excessive low-frequency polymorphic sites, which suggests that the satBaMV population was under purifying selection and/or population expansion. Further analysis of P20, the only satBaMV gene that encodes a non-structural protein involved in the long-distance movement of satBaMV, showed evidence of purifying selection. Taken together, our results suggest that purifying selection against defective P20 protein is responsible at least in part for the evolution of the satBaMV genome.
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Characterization of the cryptic AV3 promoter of ageratum yellow vein virus in prokaryotic and eukaryotic systems.
PLoS ONE
PUBLISHED: 01-01-2014
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A cryptic prokaryotic promoter, designated AV3 promoter, has been previously identified in certain begomovirus genus, including ageratum yellow vein virus isolate NT (AYVV-NT). In this study, we demonstrated that the core nucleotides in the putative -10 and -35 boxes are necessary but not sufficient for promoter activity in Escherichia coli, and showed that AYVV-NT AV3 promoter could specifically interact with single-stranded DNA-binding protein and sigma 70 of E. coli involved in transcription. Several AYVV-NT-encoded proteins were found to increase the activity of AV3 promoter. The transcription start sites downstream to AV3 promoter were mapped to nucleotide positions 803 or 805 in E. coli, and 856 in Nicotiana benthamiana. The eukaryotic activity of AV3 promoter and the translatability of a short downstream open reading frame were further confirmed by using a green fluorescent protein reporter construct in yeast (Saccharomyces cerevisiae) cells. These results suggested that AV3 promoter might be a remnant of evolution that retained cryptic activity at present.
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Chloroplast Phosphoglycerate Kinase Is Involved in the Targeting of Bamboo mosaic virus to Chloroplasts in Nicotiana benthamiana Plants.
Plant Physiol.
PUBLISHED: 10-23-2013
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The Bamboo mosaic virus (BaMV) is a positive-sense, single-stranded RNA virus. Previously, we identified that the chloroplast phosphoglycerate kinase (chl-PGK) from Nicotiana benthamiana is one of the viral RNA binding proteins involved in the BaMV infection cycle. Because chl-PGK is transported to the chloroplast, we hypothesized that chl-PGK might be involved in viral RNA localization in the chloroplasts. To test this hypothesis, we constructed two green fluorescent protein (GFP)-fused mislocalized PGK mutants, the transit peptide deletion mutant (NO TRANSIT PEPTIDE [NOTP]-PGK-GFP) and the nucleus location mutant (nuclear location signal [NLS]-PGK-GFP). Using confocal microscopy, we demonstrated that NOTP-PGK-GFP and NLS-PGK-GFP are localized in the cytoplasm and nucleus, respectively, in N. benthamiana plants. When NOTP-PGK-GFP and NLS-PGK-GFP are transiently expressed, we observed a reduction in BaMV coat protein accumulation to 47% and 27% that of the wild-type PGK-GFP, respectively. To localize viral RNA in infected cells, we employed the interaction of NLS-GFP-MS2 (phage MS2 coat protein) with the modified BaMV RNA containing the MS2 coat protein binding sequence. Using confocal microscopy, we observed that BaMV viral RNA localizes to chloroplasts. Furthermore, elongation factor1a fused with the transit peptide derived from chl-PGK or with a Rubisco small subunit can partially restore BaMV accumulation in NbPGK1-knockdown plants by helping BaMV target chloroplasts.
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A putative Rab-GTPase activation protein from Nicotiana benthamiana is important for Bamboo mosaic virus intercellular movement.
Virology
PUBLISHED: 07-06-2013
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The cDNA-amplified fragment length polymorphism technique was applied to isolate the differentially expressed genes during Bamboo mosaic virus (BaMV) infection on Nicotiana benthamiana plants. One of the upregulated genes was cloned and predicted to contain a TBC domain designated as NbRabGAP1 (Rab GTPase activation protein 1). No significant difference was observed in BaMV accumulation in the NbRabGAP1-knockdown and the control protoplasts. However, BaMV accumulation was 50% and 2% in the inoculated and systemic leaves, respectively, of the knockdown plants to those of the control plants. By measuring the spreading area of BaMV infection foci in the inoculated leaves, we found that BaMV moved less efficiently in the NbRabGAP1-knockdown plants than in the control plants. Transient expression of the wild type NbRabGAP1 significantly increases BaMV accumulation in N. benthamiana. These results suggest that NbRabGAP1 with a functional Rab-GAP activity is involved in virus movement.
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Maintaining the structural integrity of the Bamboo mosaic virus 3 untranslated region is necessary for retaining the catalytic constant for minus-strand RNA synthesis.
Virol. J.
PUBLISHED: 06-21-2013
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Bamboo mosaic virus (BaMV) and the Potato virus X (PVX) are members of the genus Potexvirus and have a single-stranded positive-sense RNA genome. The 3-untranslated region (UTR) of the BaMV RNA genome was mapped structurally into ABC (a cloverleaf-like), D (a stem-loop), and E (pseudoknot) domains. The BaMV replicase complex that was isolated from the infected plants was able to recognize the 3 UTR of PVX RNA to initiate minus-strand RNA synthesis in vitro.
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The stable association of virion with the triple-gene-block protein 3-based complex of Bamboo mosaic virus.
PLoS Pathog.
PUBLISHED: 06-01-2013
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The triple-gene-block protein 3 (TGBp3) of Bamboo mosaic virus (BaMV) is an integral endoplasmic reticulum (ER) membrane protein which is assumed to form a membrane complex to deliver the virus intracellularly. However, the virus entity that is delivered to plasmodesmata (PD) and its association with TGBp3-based complexes are not known. Results from chemical extraction and partial proteolysis of TGBp3 in membrane vesicles revealed that TGBp3 has a right-side-out membrane topology; i.e., TGBp3 has its C-terminal tail exposed to the outer surface of ER. Analyses of the TGBp3-specific immunoprecipitate of Sarkosyl-extracted TGBp3-based complex revealed that TGBp1, TGBp2, TGBp3, capsid protein (CP), replicase and viral RNA are potential constituents of virus movement complex. Substantial co-fractionation of TGBp2, TGBp3 and CP, but not TGBp1, in the early eluted gel filtration fractions in which virions were detected after TGBp3-specific immunoprecipitation suggested that the TGBp2- and TGBp3-based complex is able to stably associate with the virion. This notion was confirmed by immunogold-labeling transmission electron microscopy (TEM) of the purified virions. In addition, mutational and confocal microscopy analyses revealed that TGBp3 plays a key role in virus cell-to-cell movement by enhancing the TGBp2- and TGBp3-dependent PD localization of TGBp1. Taken together, our results suggested that the cell-to-cell movement of potexvirus requires stable association of the virion cargo with the TGBp2- and TGBp3-based membrane complex and recruitment of TGBp1 to the PD by this complex.
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A dual gene-silencing vector system for monocot and dicot plants.
Plant Biotechnol. J.
PUBLISHED: 05-23-2013
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Plant virus-based gene-silencing vectors have been extensively and successfully used to elucidate functional genomics in plants. However, only limited virus-induced gene-silencing (VIGS) vectors can be used in both monocot and dicot plants. Here, we established a dual gene-silencing vector system based on Bamboo mosaic virus (BaMV) and its satellite RNA (satBaMV). Both BaMV and satBaMV vectors could effectively silence endogenous genes in Nicotiana benthamiana and Brachypodium distachyon. The satBaMV vector could also silence the green fluorescent protein (GFP) transgene in GFP transgenic N. benthamiana. GFP transgenic plants co-agro-inoculated with BaMV and satBaMV vectors carrying sulphur and GFP genes, respectively, could simultaneously silence both genes. Moreover, the silenced plants could still survive with the silencing of genes essential for plant development such as heat-shock protein 90 (Hsp90) and Hsp70. In addition, the satBaMV- but not BaMV-based vector could enhance gene-silencing efficiency in newly emerging leaves of N. benthamiana deficient in RNA-dependant RNA polymerase 6. The dual gene-silencing vector system of BaMV and satBaMV provides a novel tool for comparative functional studies in monocot and dicot plants.
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The ex-Gaussian distribution of reaction times in adolescents with attention-deficit/hyperactivity disorder.
Res Dev Disabil
PUBLISHED: 05-23-2013
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We investigated the three parameters (mu, sigma, tau) of ex-Gaussian distribution of RT derived from the Conners continuous performance test (CCPT) and examined the moderating effects of the energetic factors (the inter-stimulus intervals (ISIs) and Blocks) among these three parameters, especially tau, an index describing the positive skew of RT distribution. We assessed 195 adolescents with DSM-IV ADHD, and 90 typically developing (TD) adolescents, aged 10-16. Participants and their parents received psychiatric interviews to confirm the diagnosis of ADHD and other psychiatric disorders. Participants also received intelligence (WISC-III) and CCPT assessments. We found that participants with ADHD had a smaller mu, and larger tau. As the ISI/Block increased, the magnitude of group difference in tau increased. Among the three ex-Gaussian parameters, tau was positively associated with omission errors, and mu was negatively associated with commission errors. The moderating effects of ISIs and Blocks on tau parameters suggested that the ex-Gaussian parameters could offer more information about the attention state in vigilance task, especially in ADHD.
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Transgenic resistance to Bamboo mosaic virus by expression of interfering satellite RNA.
Mol. Plant Pathol.
PUBLISHED: 05-16-2013
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Plant genetic engineering has broadened the options for plant virus resistance and is mostly based on pathogen-derived resistance. Previously, we have shown that interfering satellite RNA (satRNA) of Bamboo mosaic virus (satBaMV) greatly reduces Bamboo mosaic virus (BaMV) accumulation and BaMV-induced symptoms in co-inoculated plants. Here, we generated a nonviral source of virus-resistant transgenic Nicotiana benthamiana and Arabidopsis thaliana by introducing interfering satBaMV. Asymptomatic transgenic N.?benthamiana lines were highly resistant to BaMV virion and viral RNA infection, and the expression of the transgene BSL6 was higher in asymptomatic than mildly symptomatic lines. In addition, BaMV- and satBaMV-specific small RNAs were detectable only after BaMV challenge, and their levels were associated with genomic viral RNA or satRNA levels. By transcriptomic analysis, the salicylic acid (SA) signalling pathway was not induced in satBaMV transgenic A.?thaliana in mock conditions, suggesting that two major antiviral mechanisms, RNA silencing and SA-mediated resistance, are not involved directly in transgenic satBaMV-mediated BaMV interference. In contrast, resistance is associated with the level of the interfering satBaMV transgene. We propose satBaMV-mediated BaMV interference in transgenic plants by competition for replicase with BaMV.
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Characterization of the polyadenylation activity in a replicase complex from Bamboo mosaic virus-infected Nicotiana benthamiana plants.
Virology
PUBLISHED: 04-02-2013
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Bamboo mosaic virus (BaMV) has a positive-sense single-stranded RNA genome with a 5 cap and a 3 poly(A) tail. To characterize polyadenylation activity in the BaMV replicase complex, we performed the in vitro polyadenylation with various BaMV templates. We conducted a polyadenylation activity assay for BaMV RNA by using a partially purified BaMV replicase complex. The results showed that approximately 200 adenylates at the 3 end of the RNA were generated on the endogenous RNA templates. Specific fractions derived from uninfected Nicotiana benthamiana plants enhanced the polyadenylation activity, implying that host factors are involved in polyadenylation. Furthermore, polyadenylation can be detected in newly synthesized plus-strand RNA in vitro when using the exogenous BaMV minus-strand minigenome. For polyadenylation on the exogenous plus-strand minigenome, the 3 end requires at least 4A to reach 22% polyadenylation activity. The results indicate that the BaMV replicase complex recognizes the 3 end of BaMV for polyadenylation.
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The glutathione transferase of Nicotiana benthamiana NbGSTU4 plays a role in regulating the early replication of Bamboo mosaic virus.
New Phytol.
PUBLISHED: 02-25-2013
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Bamboo mosaic virus (BaMV) is a single-stranded positive-sense RNA virus. One of the plant glutathione S-transferase (GST) genes, NbGSTU4, responds as an upregulated gene in Nicotiana benthamiana post BaMV infection. In order to identify the role of NbGSTU4 in BaMV infection, the expression of NbGSTU4 was knocked down using a virus-induced gene silencing technique or was transiently expressed in N. benthamiana in BaMV inoculation. The results show a significant decrease in BaMV RNA accumulation when the expression level of NbGSTU4 is reduced; whereas the viral RNA accumulation increases when NbGSTU4 is transiently expressed. Furthermore, this study identified that the involvement of NbGSTU4 in viral RNA accumulation occurs by its participation in the viral early replication step. The findings show that the NbGSTU4 protein expressed from Escherichia coli can interact with the 3 untranslated region (UTR) of the BaMV RNA in vitro in the presence of glutathione (GSH). The addition of GSH in the in vitro replication assay shows an enhancement of minus-strand but not plus-strand RNA synthesis. The results suggest that the plant GST protein plays a role in binding viral RNA and delivering GSH to the replication complex to create a reduced condition for BaMV minus-strand RNA synthesis.
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A novel prokaryotic promoter identified in the genome of some monopartite begomoviruses.
PLoS ONE
PUBLISHED: 01-01-2013
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Geminiviruses are known to exhibit both prokaryotic and eukaryotic features in their genomes, with the ability to express their genes and even replicate in bacterial cells. We have demonstrated previously the existence of unit-length single-stranded circular DNAs of Ageratum yellow vein virus (AYVV, a species in the genus Begomovirus, family Geminiviridae) in Escherichia coli cells, which prompted our search for unknown prokaryotic functions in the begomovirus genomes. By using a promoter trapping strategy, we identified a novel prokaryotic promoter, designated AV3 promoter, in nts 762-831 of the AYVV genome. Activity assays revealed that the AV3 promoter is strong, unidirectional, and constitutive, with an endogenous downstream ribosome binding site and a translatable short open reading frame of eight amino acids. Sequence analyses suggested that the AV3 promoter might be a remnant of prokaryotic ancestors that could be related to certain promoters of bacteria from marine or freshwater environments. The discovery of the prokaryotic AV3 promoter provided further evidence for the prokaryotic origin in the evolutionary history of geminiviruses.
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Ser/Thr kinase-like protein of Nicotiana benthamiana is involved in the cell-to-cell movement of Bamboo mosaic virus.
PLoS ONE
PUBLISHED: 01-01-2013
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To investigate the plant genes affected by Bamboo mosaic virus (BaMV) infection, we applied a cDNA-amplified fragment length polymorphism technique to screen genes with differential expression. A serine/threonine kinase-like (NbSTKL) gene of Nicotiana benthamiana is upregulated after BaMV infection. NbSTKL contains the homologous domain of Ser/Thr kinase. Knocking down the expression of NbSTKL by virus-induced gene silencing reduced the accumulation of BaMV in the inoculated leaves but not in the protoplasts. The spread of GFP-expressing BaMV in the inoculated leaves is also impeded by a reduced expression of NbSTKL. These data imply that NbSTKL facilitates the cell-to-cell movement of BaMV. The subcellular localization of NbSTKL is mainly on the cell membrane, which has been confirmed by mutagenesis and fractionation experiments. Combined with the results showing that active site mutation of NbSTKL does not change its subcellular localization but significantly affects BaMV accumulation, we conclude that NbSTKL may regulate BaMV movement on the cell membrane by its kinase-like activity. Moreover, the transient expression of NbSTKL does not significantly affect the accumulation of Cucumber mosaic virus (CMV) and Potato virus X (PVX); thus, NbSTKL might be a specific protein facilitating BaMV movement.
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Phosphorylation of bamboo mosaic virus satellite RNA (satBaMV)-encoded protein P20 downregulates the formation of satBaMV-P20 ribonucleoprotein complex.
Nucleic Acids Res.
PUBLISHED: 09-28-2011
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Bamboo mosaic virus (BaMV) satellite RNA (satBaMV) depends on BaMV for its replication and encapsidation. SatBaMV-encoded P20 protein is an RNA-binding protein that facilitates satBaMV systemic movement in co-infected plants. Here, we examined phosphorylation of P20 and its regulatory functions. Recombinant P20 (rP20) was phosphorylated by host cellular kinase(s) in vitro, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and mutational analyses revealed Ser-11 as the phosphorylation site. The phosphor-mimic rP20 protein interactions with satBaMV-translated mutant P20 were affected. In overlay assay, the Asp mutation at S11 (S11D) completely abolished the self-interaction of rP20 and significantly inhibited the interaction with both the WT and S11A rP20. In chemical cross-linking assays, S11D failed to oligomerize. Electrophoretic mobility shift assay and subsequent Hill transformation analysis revealed a low affinity of the phospho-mimicking rP20 for satBaMV RNA. Substantial modulation of satBaMV RNA conformation upon interaction with nonphospho-mimic rP20 in circular dichroism analysis indicated formation of stable satBaMV ribonucleoprotein complexes. The dissimilar satBaMV translation regulation of the nonphospho- and phospho-mimic rP20 suggests that phosphorylation of P20 in the ribonucleoprotein complex converts the translation-incompetent satBaMV RNA to messenger RNA. The phospho-deficient or phospho-mimicking P20 mutant of satBaMV delayed the systemic spread of satBaMV in co-infected Nicotiana benthamiana with BaMV. Thus, satBaMV likely regulates the formation of satBaMV RNP complex during co-infection in planta.
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The interaction between bamboo mosaic virus replication protein and coat protein is critical for virus movement in plant hosts.
J. Virol.
PUBLISHED: 09-14-2011
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Bamboo mosaic virus (BaMV) is a positive-sense RNA virus belonging to the genus Potexvirus. Open reading frame 1 (ORF1) encodes the viral replication protein that consists of a capping enzyme domain, a helicase-like domain (HLD), and an RNA-dependent RNA polymerase domain from the N to C terminus. ORF5 encodes the viral coat protein (CP) required for genome encapsidation and the virus movement in plants. In this study, application of a yeast-two hybrid assay detected an interaction between the viral HLD and CP. However, the interaction did not affect the NTPase activity of the HLD. To identify the critical amino acids of CP interacting with the HLD, a random mutational library of CP was created using error-prone PCR, and the mutations adversely affecting the interaction were screened by a bacterial two-hybrid system. As a result, the mutations A209G and N210S in CP were found to weaken the interaction. To determine the significance of the interaction, the mutations were introduced into a BaMV infectious clone, and the mutational effects on viral replication, movement, and genome encapsidation were investigated. There was no effect on accumulations of BaMV CP and genomic RNAs within protoplasts; however, the virus cell-to-cell movement in plants was restricted. Sequence alignment revealed that A209 of BaMV CP is conserved in many potexviruses. Mutation of the corresponding residue in Foxtail mosaic virus CP also reduced the viral HLD-CP interaction and restricted the virus movement, suggesting that interaction between CP and a widely conserved HLD in the potexviral replication protein is crucial for viral trafficking through plasmodesmata.
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Glyceraldehyde 3-phosphate dehydrogenase negatively regulates the replication of Bamboo mosaic virus and its associated satellite RNA.
J. Virol.
PUBLISHED: 06-29-2011
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The identification of cellular proteins associated with virus replicase complexes is crucial to our understanding of virus-host interactions, influencing the host range, replication, and virulence of viruses. A previous in vitro study has demonstrated that partially purified Bamboo mosaic virus (BaMV) replicase complexes can be employed for the replication of both BaMV genomic and satellite BaMV (satBaMV) RNAs. In this study, we investigated the BaMV and satBaMV 3 untranslated region (UTR) binding proteins associated with these replicase complexes. Two cellular proteins with molecular masses of ?35 and ?55 kDa were specifically cross-linked with RNA elements, whereupon the ?35-kDa protein was identified as the glycolytic enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Gel mobility shift assays confirmed the direct interaction of GAPDH with the 3 UTR sequences, and competition gel shift analysis revealed that GAPDH binds preferentially to the positive-strand BaMV and satBaMV RNAs over the negative-strand RNAs. It was observed that the GAPDH protein binds to the pseudoknot poly(A) tail of BaMV and stem-loop-C poly(A) tail of satBaMV 3 UTR RNAs. It is important to note that knockdown of GAPDH in Nicotiana benthamiana enhances the accumulation of BaMV and satBaMV RNA; conversely, transient overexpression of GAPDH reduces the accumulation of BaMV and satBaMV RNA. The recombinant GAPDH principally inhibits the synthesis of negative-strand RNA in exogenous RdRp assays. These observations support the contention that cytosolic GAPDH participates in the negative regulation of BaMV and satBaMV RNA replication.
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Risk factors for PTSD after Typhoon Morakot among elderly people in Taiwanese aboriginal communities.
Int Psychogeriatr
PUBLISHED: 06-14-2011
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This study aimed to investigate the risk factors associated with post-traumatic stress disorder (PTSD) symptoms in a mid- and old-age population who experienced Typhoon Morakot in Taiwan.
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The hierarchical model of social interaction anxiety and depression: the critical roles of fears of evaluation.
J Anxiety Disord
PUBLISHED: 04-16-2011
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In this paper, we articulate a hierarchical model of social interaction anxiety (SIA) and depression to account for their comorbidity and the uniqueness of SIA. First, negative affect (NA) and positive affect (PA) are conceptualized as general factors shared by SIA and depression; the fear of negative evaluation (FNE) is operationalized as the specific factor, which accounts for more of the variance in SIA than in depression, and the fear of positive evaluation (FPE) is operationalized as the factor unique to SIA. FPE is the key feature that differentiates SIA from depression. Second, the proposed hierarchical model describes structural relationships among these factors, in which the higher-level factors (i.e., high NA and low PA) represent the vulnerability markers of both SIA and depression and the lower-level factors (i.e., FNE and FPE) are the dimensions of specific cognitive features. In addition, an alternative model, in which all of the relationships are the same, except that FPE is operationalized as a specific factor, is proposed to clarify the role of FPE. The results from the hierarchical regression and the structural equation modeling support the hypothesized hierarchical model. Further theoretical and practical implications for FPE and the multilevel model are discussed.
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Mutational effects of the consensus aromatic residues in the mRNA capping domain of Bamboo mosaic virus on GTP methylation and virus accumulation.
Virology
PUBLISHED: 01-11-2011
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RNA viruses classified in the alphavirus-like superfamily possess a distinct capping domain, catalyzing GTP methylation and subsequent transfer of the m(7)GMP moiety from m(7)GTP to the 5-diphosphate end of viral RNA. The H68A mutation in the capping domain of Bamboo mosaic virus enhanced GTP methylation but disabled the following transguanylation, making it possible to characterize the enzymes methyltransferase activity separately. To explore the involvement of aromatic amino acids in substrate recognition, consensus aromatic residues in the viral domain were subjected to mutational analysis in the background of H68A. Several residues, including Y126, F144, F161, Y192, Y203, Y213, and W222, were found to be critical for GTP methylation and S-adenosylmethionine (AdoMet) binding. These mutations, except for Y213, also adversely affected the GTP binding, but less extensively. In general, the mutations decreasing the activity for GTP methylation also had correspondingly detrimental effects on virus accumulation.
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One-step reverse transcription loop-mediated isothermal amplification assay for rapid detection of Cymbidium mosaic virus.
J. Virol. Methods
PUBLISHED: 01-05-2011
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Cymbidium mosaic virus (CymMV) is the most prevalent orchid virus. A single-tube one-step betaine-free reverse transcription (RT) loop-mediated isothermal amplification (LAMP) assay was developed for the rapid and easy detection of orchid-infecting CymMV. Five sets of primers were designed based on the conserved regions among various virus isolates. The specificity and the sensitivity of the assay were then evaluated using the RT-LAMP reaction. Within 1h under isothermal conditions at 60┬░C the target viral gene was amplified successfully. This RT-LAMP assay was found to be quick, specific, sensitive and easy to perform assay that involved only one step and was simpler to carry out than alternative approaches. Thus this assay is an alternative for the rapid and easy detection of CymMV in orchids. This is first time that a RT-LAMP method for the detection of an orchid virus has been described.
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Inhibitor binding increases the mechanical stability of staphylococcal nuclease.
Biophys. J.
PUBLISHED: 01-03-2011
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Staphylococcal nuclease (SNase) catalyzes the hydrolysis of DNA and RNA in a calcium-dependent fashion. We used AFM-based single-molecule force spectroscopy to investigate the mechanical stability of SNase alone and in its complex with an SNase inhibitor, deoxythymidine 3,5-bisphosphate. We found that the enzyme unfolds in an all-or-none fashion at ?26 pN. Upon binding to the inhibitor, the mechanical unfolding forces of the enzyme-inhibitor complex increase to ?50 pN. This inhibitor-induced increase in the mechanical stability of the enzyme is consistent with the increased thermodynamical stability of the complex over that of SNase. Because of its strong mechanical response to inhibitor binding, SNase, a model protein folding system, offers a unique opportunity for studying the relationship between enzyme mechanics and catalysis.
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Identification of differentially expressed genes induced by Bamboo mosaic virus infection in Nicotiana benthamiana by cDNA-amplified fragment length polymorphism.
BMC Plant Biol.
PUBLISHED: 12-27-2010
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The genes of plants can be up- or down-regulated during viral infection to influence the replication of viruses. Identification of these differentially expressed genes could shed light on the defense systems employed by plants and the mechanisms involved in the adaption of viruses to plant cells. Differential gene expression in Nicotiana benthamiana plants in response to infection with Bamboo mosaic virus (BaMV) was revealed using cDNA-amplified fragment length polymorphism (AFLP).
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[Appending Chinese language names to medicine labels: the effect on nursing staff label recognition efficacy].
Hu Li Za Zhi
PUBLISHED: 09-30-2010
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Oral medication administration error is a common occurrence in medical malpractice. While recent widespread medical order system computerization has reduced transcription errors (previously, the most prevalent medication administration error) by over 50%, oral medication administration error (previously, the second most prevalent medication administration error) has fallen by only 2%. Significant room exists for improvement in this latter error category.
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Absence of a positive bias in social anxiety: the application of a directed forgetting paradigm.
J Behav Ther Exp Psychiatry
PUBLISHED: 09-27-2010
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The present study used a directed forgetting paradigm to investigate whether socially anxious individuals show a memory bias for social information. Socially anxious and non-anxious participants viewed three types of words: socially negative, socially positive, and neutral. Each word was presented on a computer screen and was followed by a cue instructing participants to either remember or forget the word. A free recall test and a recognition test were then administered by asking participants to recall and recognize both "to-be-remembered" and "to-be-forgotten" words. When compared to non-anxious participants, socially anxious participants showed a greater directed forgetting effect for socially positive words in the free recall test, indicating that socially anxious individuals more easily forget socially positive words than do non-anxious individuals. This result suggests that socially anxious individuals lack the positive bias (i.e., difficulty in forgetting socially positive information) displayed by non-anxious individuals.
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Repositioning osteotomy for intra-articular malunion of distal radius with radiocarpal and/or distal radioulnar joint subluxation.
J Trauma
PUBLISHED: 08-12-2010
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Intra-articular malunion of the distal radius may be complicated with radiocarpal and radioulnar joint subluxation, which may result in joint stiffness and loss of function. Conventional corrective osteotomy emphasizes on the restoration of the articular step-off. However, little information is available concerning the restoration of a concentric functioning joint through osteotomy.
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Global analyses of small interfering RNAs derived from Bamboo mosaic virus and its associated satellite RNAs in different plants.
PLoS ONE
PUBLISHED: 07-08-2010
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Satellite RNAs (satRNAs), virus parasites, are exclusively associated with plant virus infection and have attracted much interest over the last 3 decades. Upon virus infection, virus-specific small interfering RNAs (vsiRNAs) are produced by dicer-like (DCL) endoribonucleases for anti-viral defense. The composition of vsiRNAs has been studied extensively; however, studies of satRNA-derived siRNAs (satsiRNAs) or siRNA profiles after satRNA co-infection are limited. Here, we report on the small RNA profiles associated with infection with Bamboo mosaic virus (BaMV) and its two satellite RNAs (satBaMVs) in Nicotiana benthamiana and Arabidopsis thaliana.
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The 3-terminal sequence of Bamboo mosaic virus minus-strand RNA interacts with RNA-dependent RNA polymerase and initiates plus-strand RNA synthesis.
Mol. Plant Pathol.
PUBLISHED: 05-08-2010
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A 3-terminal, 77-nucleotide sequence of Bamboo mosaic virus (BaMV) minus-strand RNA (Ba-77), comprising a 5 stem-loop, a spacer and a 3-CUUUU sequence, can be used to initiate plus-strand RNA synthesis in vitro. To understand the mechanism of plus-strand RNA synthesis, mutations were introduced in the 5 untranslated region of BaMV RNA, resulting in changes at the 3 end of minus-strand RNA. The results showed that at least three uridylate residues in 3-CUUUU are required and the changes at the penultimate U are deleterious to viral accumulation in Nicotiana benthamiana protoplasts. Results from UV-crosslinking and in vitro RNA-dependent RNA polymerase competition assays suggested that the replicase preferentially interacts with the stem structure of Ba-77. Finally, CMV/83 + UUUUC, a heterologus RNA, which possesses about 80 nucleotides containing the 3-CUUUU pentamer terminus, and which folds into a secondary structure similar to that of Ba-77, could be used as template for RNA production by the BaMV replicase complex in vitro.
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Mimicry of molecular pretenders: the terminal structures of satellites associated with plant RNA viruses.
RNA Biol
PUBLISHED: 03-30-2010
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Satellite RNAs (satRNAs) and satellite viruses depend on the replicase complexes provided by their cognate helper viruses and host plants for replication, pretending that they are part of the viral genomes. Although satRNAs and satellite viruses do not share significant nucleotide sequence similarity with the helper viruses, the essential cis-acting elements recognized by the replicase complexes must reside on their genomes, acting as the mimicry for the molecular pretenders. By understanding how this molecular mimicry deceives the helper viruses into supporting the satellites, a significant amount of knowledge of the basic requirements and mechanisms for replication of viruses and satellites has been obtained. Here we review the recent advances in understanding the effects of the cis elements at the termini of satRNAs and satellite viruses on their accumulation. Several well-characterized satellite/helper virus systems, representing the non-coding short satRNAs, mRNA-type long satRNAs, circular satRNAs and satellite viruses, are compared and contrasted. It is concluded that different satellites may adopt different strategies to exploit the replication/transcription/translation machineries of their helper viruses, and different mimicries may be implemented by the same molecular pretender for different biological functions.
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Arthroscopic ganglionectomy through an intrafocal cystic portal for wrist ganglia.
Arthroscopy
PUBLISHED: 02-08-2010
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A retrospective study was conducted on arthroscopic ganglionectomy in wrists using a novel intrafocal cystic portal. The safety and efficacy of this technique were assessed by treatment of 15 wrists in 15 patients.
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Single portal endoscopic carpal tunnel release: modification of Menons technique and data from 65 cases.
Int Orthop
PUBLISHED: 01-20-2010
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The purpose of our study is to make a follow-up evaluation of endoscopic carpal tunnel release under focal anesthesia using the Wolf single portal system. A total of 65 patients with a mean age of 50 years undergoing 79 procedures were retrospectively studied. Preoperative complaints, intraoperative findings, and postoperative results of all the patients were recorded. Follow-up was conducted at 1, 5, 12, and 24 weeks and at 1 year postoperatively. Wound pain, analysis of satisfaction, Levine functional status scales, and surgical complications were included. No patients sustained iatrogenic neurovascular injury or hematoma formation. The average Levine functional severity score decreased from 2.82 points preoperatively to 1.2 points at the most recent survey. One case recurred at 1 year after the surgery and subsequently underwent open release. Surgery using the Wolf single portal system under focal anesthesia is a safe and efficacious option for endoscopic carpal tunnel release.
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Satellite RNAs and Satellite Viruses of Plants.
Viruses
PUBLISHED: 10-28-2009
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The view that satellite RNAs (satRNAs) and satellite viruses are purely molecular parasites of their cognate helper viruses has changed. The molecular mechanisms underlying the synergistic and/or antagonistic interactions among satRNAs/satellite viruses, helper viruses, and host plants are beginning to be comprehended. This review aims to summarize the recent achievements in basic and practical research, with special emphasis on the involvement of RNA silencing mechanisms in the pathogenicity, population dynamics, and, possibly, the origin(s) of these subviral agents. With further research following current trends, the comprehensive understanding of satRNAs and satellite viruses could lead to new insights into the trilateral interactions among host plants, viruses, and satellites.
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The two conserved cysteine residues of the triple gene block protein 2 are critical for both cell-to-cell and systemic movement of Bamboo mosaic virus.
Mol. Plant Microbe Interact.
PUBLISHED: 10-09-2009
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The triple gene block protein 2 (TGBp2) of Bamboo mosaic virus (BaMV) is a transmembrane protein which is known to be required for the cell-to-cell movement of potexviruses. This protein has two conserved Cys residues, Cys-109 and Cys-112, at its C-terminal tail, which is supposed to be exposed on the outer surface of the endoplasmic reticulum (ER) membrane and ER-derived granular vesicles. In this study, we investigated the importance of these two Cys residues on the cell-to-cell and systemic movement of BaMV. Our results indicate that the Cys-to-Ala substitutions in TGBp2 make the cell-to-cell movement of BaMV relatively inefficient and the systemic movement of BaMV severely inhibited. Moreover, the defect in systemic movement is attributed to the inefficient transport of viral RNA in the phloem of petiole. Clearly, TGBp2 is critical not only for the cell-to-cell but also for the systemic movement of BaMV. In addition, the conserved Cys residues are important for the functioning of TGBp2.
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Deficits in interval timing measured by the dual-task paradigm among children and adolescents with attention-deficit/hyperactivity disorder.
J Child Psychol Psychiatry
PUBLISHED: 09-15-2009
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The underlying mechanism of time perception deficit in long time intervals in attention-deficit/hyperactivity disorder (ADHD) is still unclear. This study used the time reproduction dual task to explore the role of the attentional resource in time perception deficits among children and adolescents with ADHD.
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Identification and functional characterization of regions that can be crosslinked to RNA in the helicase-like domain of BaMV replicase.
Virology
PUBLISHED: 04-12-2009
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The helicase-like domain of the Bamboo mosaic virus replicase catalyzes the release of 5-gamma-phosphate from both ATP and 5-triphosphated RNA by an identical set of catalytic residues with a presumably larger binding pocket for RNA. In this study, the peptidyl regions involved in RNA binding were mapped by reversible formaldehyde crosslinking and mass spectrometry. Eleven residues within these regions were examined by mutational analysis. H636A, Y704A, and K706A greatly diminished the enzymatic activities and were unable to support the viral replication in Nicotiana benthamiana protoplasts. K843A decreased activity toward the RNA substrate to 17% of WT, and approximately 20% replication efficiency was retained in protoplasts. R597A and K610A retained approximately 50 and approximately 90% of the enzymatic activities, respectively. However, replication in protoplasts of these mutants was extremely limited. Proteins with the mutations K603A, R628A, R645A, H794A, and R799A were present at levels 30-69% of WT in protoplasts. However, the fates of these mutations in plants were different. Viral cell-to-cell movement was limited by the K603A and R628A mutations, while systemic movement was restricted by R645A and H794A. The implications of the helicase-like domain in the viral replication and movement are discussed.
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Suppression of bamboo mosaic virus accumulation by a putative methyltransferase in Nicotiana benthamiana.
J. Virol.
PUBLISHED: 03-18-2009
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Bamboo mosaic virus (BaMV) is a 6.4-kb positive-sense RNA virus belonging to the genus Potexvirus of the family Flexiviridae. The 155-kDa viral replicase, the product of ORF1, comprises an N-terminal S-adenosyl-l-methionine (AdoMet)-dependent guanylyltransferase, a nucleoside triphosphatase/RNA 5-triphosphatase, and a C-terminal RNA-dependent RNA polymerase (RdRp). To search for cellular factors potentially involved in the regulation of replication and/or transcription of BaMV, the viral RdRp domain was targeted as bait to screen against a leaf cDNA library of Nicotiana benthamiana using a yeast two-hybrid system. A putative methyltransferase (PNbMTS1) of 617 amino acid residues without an established physiological function was identified. Cotransfection of N. benthamiana protoplasts with a BaMV infectious clone and the PNbMTS1-expressing plasmid showed a PNbMTS1 dosage-dependent inhibitory effect on the accumulation of BaMV coat protein. Deletion of the N-terminal 36 amino acids, deletion of a predicted signal peptide or transmembrane segment, or mutations in the putative AdoMet-binding motifs of PNbMTS1 abolished the inhibitory effect. In contrast, suppression of PNbMTS1 by virus-induced gene silencing in N. benthamiana increased accumulation of the viral coat protein as well as the viral genomic RNA. Collectively, PNbMTS1 may function as an innate defense protein against the accumulation of BaMV through an uncharacterized mechanism.
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Characterization of the RNA-binding properties of the triple-gene-block protein 2 of Bamboo mosaic virus.
Virol. J.
PUBLISHED: 03-05-2009
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The triple-gene-block protein 2 (TGBp2) of Bamboo mosaic virus (BaMV) is a transmembrane protein which was proposed to be involved in viral RNA binding during virus transport. Here, we report on the RNA-binding properties of TGBp2. Using tyrosine fluorescence spectroscopy and UV-crosslinking assays, the TGBp2 solubilized with Triton X-100 was found to interact with viral RNA in a non-specific manner. These results raise the possibility that TGBp2 facilitates intracellular delivery of viral RNA through non-specific protein-RNA interaction.
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Subcellular localization and expression of bamboo mosaic virus satellite RNA-encoded protein.
J. Gen. Virol.
PUBLISHED: 01-15-2009
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The satellite RNA of bamboo mosaic virus (satBaMV) has a single open reading frame encoding a non-structural protein, P20, which facilitates long-distance movement of satBaMV in BaMV and satBaMV co-infected plants. Immunohistochemistry and immunoelectron microscopy revealed that the P20 protein accumulated in the cytoplasm and nuclei in co-infected cells. P20 and the helper virus coat protein (CP) were highly similar in their subcellular localization, except that aggregates of BaMV virions were not labelled with anti-P20 serum. The BaMV CP protein was fairly abundant in mesophyll cells, whilst P20 was more frequently detected in mesophyll cells and vascular tissues. The expression kinetics of the P20 protein was similar to but slightly earlier than that of CP in co-infected Bambusa oldhamii protoplasts and Nicotiana benthamiana leaves. However, satBaMV-encoded protein levels declined rapidly in the late phase of co-infection. During co-infection, in addition to the intact P20, a low-molecular-mass polypeptide of 16 kDa was identified as a P20 C-terminally truncated product; the possible method of generation of the truncated protein is discussed.
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Structural and functional analyses of the 3 untranslated region of Bamboo mosaic virus satellite RNA.
Virology
PUBLISHED: 01-10-2009
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The 3-untranslated region (UTR) of RNA genomes of viruses and satellite RNAs plays essential roles in viral replication and transcription. The structural features of the 3-UTR of the satellite RNA of Bamboo mosaic virus (satBaMV) involved in its replication were analyzed in this study. By the use of enzymatic probing, the secondary structure of satBaMV 3-UTR was confirmed to comprise two small stem-loops (SLA and SLB), one large stem-loop (SLC), and a poly(A) tail of mainly 75-200 adenylate residues, which is similar to those on the genomic RNA of the helper virus, BaMV. Five sets of mutants of satBaMV were constructed to analyze the biological functions of the structural elements of the 3-UTR. The data revealed that both the polyadenylation signal and poly(A) tail are required for satBaMV RNA replication. The structural conservation of SLA, SLB, and SLC is also important for efficient satBaMV accumulation, whereas the nucleotides in these regions may also possess sequence-specific functions. In contrast to the requirement for the accumulation of BaMV genomic RNA, mutations in the conserved hexanucleotide (ACCUAA) in the loop region of SLC had limited effect on the accumulation of satBaMV RNA. In addition, replacing the 5-, 3-UTR, or both regions of satBaMV by those of BaMV greatly decreased the accumulation of satBaMV RNA. Taken together, these data indicate that satBaMV might have adopted a 3-UTR structure similar to that of BaMV but may have evolved distinct features for its efficient replication.
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Unusual roles of host metabolic enzymes and housekeeping proteins in plant virus replication.
Curr Opin Virol
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Viruses have developed the ability to improvise their own replication machineries with host proteins, adapt to different environments, and overcome difficulties encountered during various stages of their infection cycles. The modular nature of protein functional motifs allows for the novel use of ordinary host factors. Recent studies have revealed that positive-sense RNA [(+)RNA] viruses may adapt regular metabolic enzymes and housekeeping proteins of host plants by exploiting unusual functions to accommodate their need for replication, mainly for recruitment and subcellular localization of RNA templates or components of replicase complexes and for controlling switches in different stages of replication. This review compares the newly discovered roles of selected metabolic enzymes and housekeeping proteins in plant (+)RNA virus replication with their original cellular functions and the different consequences when utilized by different viruses.
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Hsp90 interacts specifically with viral RNA and differentially regulates replication initiation of Bamboo mosaic virus and associated satellite RNA.
PLoS Pathog.
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Host factors play crucial roles in the replication of plus-strand RNA viruses. In this report, a heat shock protein 90 homologue of Nicotiana benthamiana, NbHsp90, was identified in association with partially purified replicase complexes from BaMV-infected tissue, and shown to specifically interact with the 3 untranslated region (3 UTR) of BaMV genomic RNA, but not with the 3 UTR of BaMV-associated satellite RNA (satBaMV RNA) or that of genomic RNA of other viruses, such as Potato virus X (PVX) or Cucumber mosaic virus (CMV). Mutational analyses revealed that the interaction occurs between the middle domain of NbHsp90 and domain E of the BaMV 3 UTR. The knockdown or inhibition of NbHsp90 suppressed BaMV infectivity, but not that of satBaMV RNA, PVX, or CMV in N. benthamiana. Time-course analysis further revealed that the inhibitory effect of 17-AAG is significant only during the immediate early stages of BaMV replication. Moreover, yeast two-hybrid and GST pull-down assays demonstrated the existence of an interaction between NbHsp90 and the BaMV RNA-dependent RNA polymerase. These results reveal a novel role for NbHsp90 in the selective enhancement of BaMV replication, most likely through direct interaction with the 3 UTR of BaMV RNA during the initiation of BaMV RNA replication.
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Functional analysis of the conserved histidine residue of Bamboo mosaic virus capping enzyme in the activity for the formation of the covalent enzyme-m7GMP intermediate.
FEBS Lett.
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The alphavirus-like mRNA capping enzyme of Bamboo mosaic virus (BaMV) exhibits an AdoMet-dependent guanylyltransferase activity by which the methyl group of AdoMet is transferred to GTP, leading to the formation of m(7)GTP, and the m(7)GMP moiety is next transferred to the 5 end of ppRNA via a covalent enzyme-m(7)GMP intermediate. The function of the conserved H68 of the BaMV capping enzyme in the intermediate formation was analyzed by mutagenesis in this study. The nature of the bond linking the enzyme and m(7)GMP was changed in the H68C mutant protein, strongly suggesting that H68 covalently binds to m(7)GMP in the intermediate.
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Mental adjustment at different phases in breast cancer trajectory: re-examination of factor structure of the Mini-MAC and its correlation with distress.
Psychooncology
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The aim of this study is twofold. First, it aims to determine the factor structure of the Mini-Mental Adjustment to Cancer (Mini-MAC) Scale by using confirmatory factor analysis (CFA) to compare the three-factor, four-factor, and five-factor structures among 340 Taiwanese breast cancer patients. Second, it aims to test the difference in the correlations of coping strategies and the outcome measures between two populations: one-month newly diagnosed and five-year long-term survival patients.
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Induction of protective immunity in chickens immunized with plant-made chimeric Bamboo mosaic virus particles expressing very virulent Infectious bursal disease virus antigen.
Virus Res.
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Very virulent Infectious bursal disease virus (vvIBDV) causes a highly contagious disease in young chickens and leads to significant economic loss in the poultry industry. Effective new vaccines are urgently needed. Autonomously replicating plant virus-based vector provides attractive means for producing chimeric virus particles (CVPs) in plants that can be developed into vaccines. In this study, we demonstrate the potential for vaccine development of Bamboo mosaic virus (BaMV) epitope-presentation system, where the antigen from vvIBDV VP2 was fused to the N-terminus of BaMV coat protein. Accordingly, an infections plasmid, pBIBD2, was constructed. Inoculation of the recombinant BaMV clone pBIBD2 enabled the generation of chimeric virus, BIBD2, and stable expression of IBDV VP2 antigen on its coat protein. After intramuscular immunization with BIBD2 CVPs, chickens produced antibodies against IBDV and were protected from vvIBDV (V263/TW strain) challenges. These results corroborate the feasibility of BaMV-based CVP platform in plants for the development and production of vaccines against IBDV.
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The conserved 5 apical hairpin stem loops of bamboo mosaic virus and its satellite RNA contribute to replication competence.
Nucleic Acids Res.
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Satellite RNAs associated with Bamboo mosaic virus (satBaMVs) depend on BaMV for replication and encapsidation. Certain satBaMVs isolated from natural fields significantly interfere with BaMV replication. The 5 apical hairpin stem loop (AHSL) of satBaMV is the major determinant in interference with BaMV replication. In this study, by in vivo competition assay, we revealed that the sequence and structure of AHSL, along with specific nucleotides (C(60) and C(83)) required for interference with BaMV replication, are also involved in replication competition among satBaMV variants. Moreover, all of the 5 ends of natural BaMV isolates contain the similar AHSLs having conserved nucleotides (C(64) and C(86)) with those of interfering satBaMVs, suggesting their co-evolution. Mutational analyses revealed that C(86) was essential for BaMV replication, and that replacement of C(64) with U reduced replication efficiency. The non-interfering satBaMV interfered with BaMV replication with the BaMV-C64U mutant as helper. These findings suggest that two cytosines at the equivalent positions in the AHSLs of BaMV and satBaMV play a crucial role in replication competence. The downregulation level, which is dependent upon the molar ratio of interfering satBaMV to BaMV, implies that there is competition for limited replication machinery.
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